Modular joint prosthesis augmentation system

Abstract

A modular joint prosthesis system includes an articulation member, such as a cruciate retaining femoral component of a knee joint prosthesis, having a superior bone engaging surface, an inferior articulation surface and one or more fixation pegs extending from the superior surface. An augmentation block mounts on the superior surface of the articulation member and has an aperture surrounding a respective fixation peg. The system further includes a compression collet seated between the aperture of the augmentation block and the fixation peg. In assembly, a securement device mounted over the fixation peg compresses the compression collet so as to engage the fixation peg and maintain the augmentation block on the articulation member.

What is claimed is: 
     
       1. A modular joint prosthesis system, comprising: at least one articulation member having a superior bone engaging surface and an inferior articulation surface, the superior surface including at least one fixation peg member extending superiorly therefrom;   at least one augmentation block having a superior bone engaging surface, an inferior surface that mounts upon the superior surface of the articulation member and an aperture extending between the superior and inferior surfaces, the aperture having dimensions suitable to surround the at least one fixation peg member;   at least one compression collet having a size and shape effective to be seated between the aperture of the augmentation block and the at least one fixation peg member, wherein the at least one compression collet is engaged within the aperture; and   at least one securement device mountable to the at least one fixation peg member to compress the at least one compression collet so as to engage the at least one fixation peg member and maintain the augmentation block upon the articulation member.   
     
     
       2. The system of claim 1 wherein the at least one articulation member is a femoral component of a knee joint prosthesis. 
     
     
       3. The system of claim 2 wherein the femoral component is a cruciate retaining femoral component with a first fixation peg member extending from a medial distal flat of the femoral component and a second fixation peg member extending from a lateral distal flat of the femoral component. 
     
     
       4. The system of claim 3 wherein the at least one compression collet comprises: a base portion which seats within the aperture of the at least one augmentation block; and   a plurality of compressible members extending from the base portion.   
     
     
       5. The system of claim 4 wherein the at least one compression collet further comprises an intermediate, externally threaded portion disposed between the base portion and the compressible members. 
     
     
       6. The system of claim 5 wherein the compressible members define a substantially circular opening having an inner diameter slightly greater than, less than or equal to the diameter of the at least one fixation peg member. 
     
     
       7. The system of claim 6 wherein the inner diameter of the opening defined by the compressible members tapers from a distal portion thereof adjacent to the intermediate portion to a proximal portion thereof. 
     
     
       8. The system of claim 6 wherein the at least one securement device comprises a nut having internal threads matable with the external threads of the at least one compression collet. 
     
     
       9. The system of claim 3 wherein the aperture of the at least one augmentation block is elongated in the medial-lateral direction. 
     
     
       10. The system of claim 9 wherein the at least one compression collet comprises: a base portion, elongated in the medial-lateral direction, which seats within the aperture of the at least one augmentation block;   an intermediate, externally threaded portion; and   a plurality of compressible members extending from the intermediate portion.   
     
     
       11. The system of claim 10 wherein the intermediate portion of the at least one compression collet is disposed on the base portion offset from a center point of the base portion. 
     
     
       12. The system of claim 4 wherein the base portion of the at least one compression collet is frictionally engaged with the aperture of the at least one augmentation block. 
     
     
       13. The system of claim 3 wherein the aperture of the at least one augmentation block is substantially circular. 
     
     
       14. The system of claim 13 wherein the aperture of the at least one augmentation block is defined by a threaded inner wall. 
     
     
       15. The system of claim 14 wherein the at least one compression collet is substantially circular having an annular collar and a plurality of compressible members extending from the collar. 
     
     
       16. The system of claim 15 wherein the collar has an outermost diameter slightly greater than or equal to a diameter of the aperture of the at least one augmentation block. 
     
     
       17. The system of claim 16 wherein the at least one securement device comprises an annular nut having external threads matable with the threaded inner wall of the aperture of the at least one augmentation block, and an inner diameter with dimensions suitable to compress the compressible members of the at least one compression collet against the at least one fixation peg member upon mating with the at least one augmentation block. 
     
     
       18. The system of claim 16 wherein internal surfaces of the compressible members include surface features to enhance engagement with the at least one fixation peg member. 
     
     
       19. A modular joint prosthesis system, comprising: at least one articulation member having a superior bone engaging surface and an inferior articulation surface, the superior surface including at least one fixation peg member extending superiorly therefrom;   at least one augmentation block having a superior bone engaging surface, an inferior surface that mounts upon the superior surface of the at least one articulation member and an aperture extending between the superior and inferior surfaces, the aperture having dimensions suitable to surround the at least one fixation peg member;   at least one compression collet comprising: a base portion which seats within the aperture of the at least one augmentation block; an intermediate portion; and   a plurality of compressible members extending from the intermediate portion; and     at least one securement device matable with the intermediate portion of the at least one compression collet to compress the at least one compression collet so as to engage the at least one fixation peg member and maintain the at least one augmentation block upon the at least one articulation member.   
     
     
       20. The system of claim 19 wherein the intermediate portion of the at least one compression collet has external threads and the at least one securement device has internal threads matable with the external threads of the intermediate portion. 
     
     
       21. The system of claim 19 wherein the aperture of the at least one augmentation block is elongated in the medial-lateral direction and the base portion of the at least one compression collet is elongated in the medial-lateral direction. 
     
     
       22. The system of claim 19 wherein the compressible members define an opening which tapers from a distal portion thereof adjacent to the intermediate portion of the at least one compression collet to a proximal portion thereof. 
     
     
       23. The system of claim 19 wherein the base portion of the at least one compression collet is frictionally engaged with the aperture of the at least one augmentation block. 
     
     
       24. A modular joint prosthesis system, comprising: at least one articulation member having a superior bone engaging surface and an inferior articulation surface, the superior surface including at least one fixation peg member extending superiorly therefrom;   at least one augmentation block having a superior bone engaging surface, an inferior surface that mounts upon the superior surface of the at least one articulation member and an aperture extending between the superior and inferior surfaces, the aperture having dimensions suitable to surround the at least one fixation peg member;   at least one compression collet having an annular collar and a plurality of compressible members extending from the collar; and   at least one securement device matable with the aperture of the at least one augmentation block to compress the at least one compression collet so as to engage the at least one fixation peg member and maintain the at least one augmentation block upon the at least one articulation member.   
     
     
       25. The system of claim 24 wherein the aperture of the at least one augmentation block is substantially circular and is defined by a threaded inner wall and the at least one securement device has external threads matable with the threaded inner wall of the aperture of the at least one augmentation block. 
     
     
       26. The system of claim 24 wherein internal surfaces of the compressible members include surface features to enhance engagement with the at least one fixation peg member.